Exercise devices using a friction resistance principle are well known in the prior art. A number of these devices have been developed and used in the past, but in general they have not been completely accepted by the public. Their commercial success has been somewhat limited because of their several disadvantages, which will be discussed in more detail below.
One family of friction resistance exercising devices is shown in U.S. Pat. Nos. 3,197,204; 3,411,776; and 3,717,339, all of which issued to HOLKESVICK et al. These devices appear to have a number of characteristics which would make their operation and use less than completely satisfactory. In the HOLKESVICK et al. devices the rope 62 wraps around a solid metal shaft 22 which, because it is solid, retains and builds up heat. The rope 62 passes through slots 44 in the lower hub 40. Because the slots 44 are so small, the rope also generates a lot of heat. Certain embodiments of the device have end plugs 66 which require expensive tooling. Lastly, the adjustment of lower hub 40 can be changed only on a notch-by-notch basis, which makes it difficult to quickly change the adjustment to any desired setting.
Another friction resistance type exercising device is shown in U.S. Pat. No. 3,591,174 to SILBERMAN. This device also has a solid shaft 22 which tends to build up heat. Case 16 is in direct contact with shaft 22, enclosing the heat and directing it downward. Shaft 22 also requires elaborate and expensive tooling. Rope 32 passes through guides 34 and 38 which are only slightly larger than the rope. These guides generate heat and cause excessive wear on rope 32.
Still another friction resistance rope exercising device is shown in U.S. Pat. No. 3,782,722 to WEBB. The WEBB device also has an end knob 36 with holes 48 and 49 which are only slightly larger than the rope; thus this device tends to quickly wear out the rope and builds up excessive heat. In the WEBB device, rope 11 wraps around solid shaft 18, which again has the characteristic of retaining and building up heat. Solid shaft 18 is a part requiring elaborate and expensive tooling. Tension on rope 11 is adjustable with end knob 36, which rotates and can only change settings every 60 degrees.
Two additional rope friction exercising devices are shown in U.S. Pat. No. 3,614,098 to CARR and U.S. Pat. No. 3,674,261 to KRUG. The CARR device has an outer sleeve 11 with a wedge-shaped hollow interior and a solid wedge 21 which is insertable within the sleeve. A rope 43 passes about the solid wedge 21 so as to be frictionally engaged between the wedge 21 and the interior of the sleeve 11. This device appears to provide a structure which is impractical because of excessive wear on the rope 43. The KRUG device appears to be an elaborate device having a number of machined and threaded parts. This device appears to be expensive to manufacture and therefore would not be practical from a commercial standpoint.
Two other devices which use rope friction in a braking type device are shown in U.S. Pat. No. 536,866 to FITZ GERALD and U.S. Pat. No. 3,532,189 to WADE. The former patent to FITZ GERALD discloses a fire escape device utilizing a friction resistance principle in order to lower oneself on a rope. The latter device to WADE is an adjustable friction resistance brake device having general use as a rope exercise device or a rope brake device.
Most of the above-mentioned prior art devices are rope friction devices having solid metal parts which retain and build up heat. All of these devices have narrow channels through which the rope must pass. In all cases, this tends to wear out the rope and also to build up heat at the point where the rope passes through the opening or channel. Moreover, these prior art devices are elaborate devices having numerous parts, many of which require expensive machining and tooling. Thus, the devices are labor intensive and expensive to manufacture.
In view of the foregoing discussion it will be apparent that the prior art devices do not provide an exercise device which is particularly well suited for swimmers. Moreover, these prior art devices do not provide a rope exercise device which is simple, inexpensive to manufacture, dissipates heat well, and does not wear out the rope.
It is, therefore, an object of this invention to provide a friction resistance exercise device which causes the user to simulate the exercise obtained in swimming a crawl stroke.
It is another object of the invention to provide a friction resistance exercise device which is well engineered from the standpoint of heat dissipation and therefore has parts designed to dissipate heat and not to retain it.
It is still another object of the invention to provide a rope friction resistance exercise device which is designed to minimize wear on the rope.
It is yet another object of the invention to provide a friction resistance exercise device which is simple and has no expensive machined or threaded parts and which is easy and inexpensive to manufacture.